[FEATURE] Support customized context in function eko.generate()

[leinue]

Feature Summary

Add customized context in function eko.generate()

Use Case

Before executing the workflow, there may be a more complex intent recognition process and contextual information that needs to be conveyed. In this case, it is desired to customize the context before generating the workflow.

Expected Use case

eko.generate(`my workflow`, { 
    context: `my context`
})

Expected Outcome

No response

Additional Context

No response